JPS63236321A - X-ray exposure device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] The first reflective optical system irradiates and exposes a mask using part of the synchrotron radiation, and furthermore, separate from this, a part of the synchrotron radiation is used to irradiate the mask with an axis slightly inclined to the central axis of incidence of the synchrotron radiation. By irradiating and exposing the mask using the other part of the synchrotron radiation using the first reflective optical system and the second reflective optical system having 180° rotational symmetry with the axis of symmetry, the change in exposure amount due to the change in the reflection angle is suppressed. X-ray exposure equipment that corrects and increases exposure uniformity.

[Industrial application field]

The present invention utilizes synchrotron radiation (Synchrotron radiation).
nRadiation) related to X-ray exposure equipment,
More particularly, the present invention relates to an X-ray exposure apparatus equipped with a method for increasing exposure uniformity.

When electrons moving at a speed close to the speed of light are accelerated along a circular orbit, they emit continuous electromagnetic waves spanning a wide range of wavelengths from infrared to X-rays in the tangential direction of the circular orbit. This is synchrotron radiation.

On the other hand, lithography using soft X-rays has fewer problems due to the influence of diffraction as in ultraviolet exposure or scattering of electrons incident on the resist as in electron beam exposure, and high resolution can be obtained. However, with electron beam excitation type X-ray sources, the luminous flux is broken and has low brightness, so
The throughput was low and it was difficult to put it into practical use.

When this synchrotron radiation light, that is, the soft X-rays in the synchrotron radiation light is used, it is optimal as a radiation source for lithography because it is strong, stable, and has good directivity.

However, since the light emitted by the electrons circulating in the electron storage ring is emitted only in the tangential direction, the vertical spread of this emitted light is about 1 mrad. Therefore, only a band-shaped light beam spread thinly in the horizontal direction is obtained, but there is a drawback that a mask pattern having a two-dimensional spread cannot be transferred all at once.

For this reason, a method has been considered in which a reflecting mirror is provided in the optical path and the reflecting mirror is slightly oscillated to scan the band-shaped emitted light back and forth in the vertical direction. The size of this belt-shaped emitted light beam is approximately 5 mm in height and 50 mm in width at the reflecting mirror position.

At this time, sufficient reflectance cannot be obtained unless the angle at which the emitted light is incident on the reflecting mirror is a shallow angle with an angle of attack (complementary angle to the angle of incidence) of 1.56 or less. Also, even within this range,
There is a problem in that a slight change in the angle of attack changes the intensity and wavelength of the reflected radiation, making it impossible to uniformly expose the required exposure area. Uniform exposure is an important condition for microfabrication, and improvements in this respect have been desired for a long time.

[Conventional technology]

FIG. 3 is a schematic diagram for explaining a conventional X-ray exposure apparatus, in which (a) is a perspective view of the exposure apparatus, and (b) is an exposure area diagram.

In FIG. 3(a), the synchrotron radiation 1 has the line shown as the center light of the luminous flux, its incident direction is the horizontal Z-1-2-2 direction, and its spread is as follows before entering the reflective optical system. Cut the uneven part of the brightness distribution with a slit and cut it in the height direction by about 5
mm, approximately 50 mm in the lateral direction. This emitted light l is incident on the lower surface of the first reflecting mirror (plane mirror) 2 from the left side of the figure. This first reflecting mirror 2 can be rotated by a small angle around a horizontal axis X, 1-X, 2 perpendicular to the Z, 1-Z, 2 direction, and the emitted light 1 to this first reflecting mirror 2 is The incident situation is as shown in the upper left of this figure.

The reflected radiation 1 enters the first reflecting mirror 2 at an angle of attack θ (θ=l 4 mrad), and the reflected radiation 1 enters the second reflecting mirror 2, which has a cylindrical surface as a mirror surface.
It enters the reflecting mirror (toroidal mirror) 3 at the same small angle of attack and is reflected, and becomes reflected light 6-1, which forms a horizontally elongated first exposure spot PA area on the surface of the X-ray mask 4. form. As a result, the pattern of the mask is transferred onto a substrate 5 such as a semiconductor wafer placed behind the mask 4.

The reason why the second reflecting mirror 3 is a toroidal mirror is to narrow down the emitted light that diverges in the horizontal direction.

Next, when the first reflecting mirror 2 slightly rotates in the direction of the arrow and comes to the position shown by the dotted line, the angle of attack at the first reflecting mirror 2 becomes θ+Δθ, and the reflected light is emitted as shown by the dotted line.

This reflected radiation is further reflected by the second reflecting mirror 3 to form a second exposure spot P on the mask 4 as reflected light 6-2.

Therefore, when the first reflecting mirror 2 rotates in the direction of the arrow to scan the mask surface, the exposure spot changes to the first exposure spot P.
From A, it moves in the direction of the arrow while changing its shape to the second exposure spot PR. Note that the synchrotron radiation taken out from the electron storage ring contains strong gamma rays, which travel in a straight line. The area is avoided to form an exposed area.

In FIG. 3(b), the first exposure spot PA has an upwardly curved arc shape and has a horizontal width of about 80 mm and a vertical width of about 5 mm. The second exposure spot P8 is also the same as the first exposure spot P.
Like A, it has an upwardly curved arc shape, and the vertical width is about 5 mm.
1, but its width is narrow, about 45 mm.

As the first reflecting mirror 2 rotates, the exposure spot moves from bottom to top as shown by the arrow, and the first exposure spot PA and second exposure spot
The area between the R light spots PB becomes the exposure area 8.

Since the first exposure spot PA is reflected light at a shallow angle of attack, it contains more short-wavelength radiation than the second exposure spot PR, and therefore the radiation intensity is about 10 to 20%.
Becomes large. Therefore, in this exposure region 8, the exposure intensity is high in the lower part and small in the upper part, which causes unevenness in the amount of exposure. In microfabrication, the exposure amount must be made as uniform as possible because the unevenness of the exposure amount causes unevenness in pattern dimensions.

[Problem that the invention seeks to solve]

When the reflector is rotated to scan the mask surface with the exposure spot, there is an unevenness in the exposure intensity: when the radiation light incident on the reflector has a shallow angle of attack, the exposure intensity is large, and when the angle of attack is large, the exposure intensity is small. . Eliminate this unevenness in exposure.

[Means for solving problems]

The solution to the above problem is that in an apparatus that projects and exposes a mask pattern onto a substrate using synchrotron radiation, a part of the first block of synchrotron radiation is received. The first reflecting optical system deflects the emitted light by changing the incident angle of a reflecting mirror to irradiate and scan the pattern on the mask, and rotates in a direction tilted by a small angle with respect to the direction of the central axis of incidence of the emitted light. a second reflective optical system having rotational symmetry of 180° with the first reflective optical system, the axis of symmetry being 180° rotationally symmetrical;
The second reflective optical system receives the second block of radiation, which is another part of the radiation, and deflects the received radiation by changing the incident angle of the reflecting mirror, thereby forming a pattern on the mask. This is achieved by an X-ray exposure device according to the invention that scans the irradiation.

[Effect]

A first reflective optical system that receives a part of the synchrotron radiation by a first reflective optical system, forms an exposure area by the first reflective optical system, and has an axis of rotational symmetry with an axis slightly tilted from the direction of incidence of the synchrotron radiation. Another part of the emitted light is received by a second reflective optical system having 1806 rotational symmetry, and the exposed area by the second reflective optical system is formed to overlap the exposed area by the first reflective optical system. Since the exposure intensity distribution formed by the first reflective optical system and that formed by the second reflective optical system are exactly opposite, uneven exposure intensity can be canceled out and uniform exposure can be obtained.

(Example) FIG. 1 is a schematic diagram for explaining an XvA exposure apparatus according to the present invention, in which (a) is a perspective view of the exposure apparatus, and (b) is an exposure area diagram.

In FIG. 1(a), the operation of a first reflective optical system 10 composed of a first reflective mirror 2 and a second reflective mirror 3 is almost the same as that of a conventional reflective optical system.

In this figure, the incident direction of the central light is horizontal Z・1
- The right half of the first block of synchrotron radiation 1 (as seen from the synchrotron radiation traveling direction), which is the Z. Receive light.

This first reflecting mirror 2 can rotate by a small angle around a horizontal axis X-1-X-2 perpendicular to the Z-1-Z-2 direction.
The right side radiation light 1-1 enters the first reflecting mirror 2 at a small angle of attack, and the reflected radiation light enters the second reflecting mirror (toroidal mirror) 3 whose cylindrical surface is a mirror surface at a similar small angle of attack. The reflected light 6-1 forms a horizontally elongated first exposure spot PA of the right-side emitted light on the surface of the mask 4.

The second reflecting mirror 3 not only reflects the downwardly incident radiant beam upward, but also slightly deflects it to the left.

As a result, the pattern of the mask is transferred onto the substrate 5, such as a semiconductor wafer 8, placed behind the mask 4.

Then, when the first reflecting mirror 2 rotates slightly in the direction of the arrow,
The reflected light exiting the first reflecting mirror 2 is emitted as reflected light indicated by a dotted line. This reflected radiation is further reflected by the second reflecting mirror 3 and projected onto the mask 4 as reflected light 6-2, forming a second exposure spot Pg of the right side radiation.

As in the conventional example, the first exposure spot PA of the right side emitted light has a wider spread in the lateral direction and has a higher exposure intensity than the second exposure spot PR of the right side emitted light.

Next, for the second block of synchronized light, which is the left half of the luminous flux of the synchronized light 1, that is, the left synchronized light 1-2, a third reflective mirror 12 and a fourth reflective mirror, which have the same configuration as the first reflective optical system, are used. Mirror 13
Reflection and deflection are performed using a second reflection optical system 20 configured as follows. The second reflective optical system 20 is installed with respect to the first reflective optical system 10 as follows.

The above-mentioned first reflection optical system has a rotationally symmetrical axis of the W-1-W-2 axis which is tilted downward by a minute angle δ with respect to the Z-1-Z-2 direction which is the central axis direction of the luminous flux of the synchrotron radiation 1. Series 10 and 180
The second reflective optical system 20 is installed six-fold symmetrically. Furthermore, W.
The 1-W.2 axis passes through the intersection 9 of the X-1-X.2 axis and the Z.1-Z.2 axis, which are the rotation axes of the first reflecting mirror 2 and the third reflecting mirror 120.

In this way, the left side emitted light 1-2 is incident on the upper surface of the third reflecting mirror (plane mirror) 12 at a small angle of attack, and is reflected upward. This reflected light is transmitted to a fourth reflecting mirror (with a cylindrical reflecting surface on the lower surface)
The light enters the toroidal mirror (toroidal mirror) 13 at the same small angle of attack, is reflected and deflected slightly to the right, becomes reflected light 7-1, and is reflected onto the surface of the mask 4 at the first exposure slot 7 of the left side emitted light. A spot QA is formed so as to overlap the first exposure spot PA of the right-side emitted light. However, since the first exposure spot Q of the left-side radiation light is formed at a relatively large angle of attack, it has the same spread size as the second exposure spot PR of the right-side radiation light, and is downwardly exposed. It has a curved arc shape.

Then, when the third reflecting mirror 12 is slightly rotated in the direction of the arrow, the reflecting mirror exiting the third reflecting mirror 12 is emitted as reflected light shown by a dotted line. This reflected light is further reflected by the fourth reflecting mirror 13 and projected onto the mask 4 as reflected light 7-2, forming a second exposure spot QB of the left-side emitted light. As the third reflecting mirror 12 is rotated, the angle of attack of the radiation light becomes smaller, so that the second exposure spot Q of the left radiation light becomes wider in the lateral direction than the first exposure spot Qa of the left radiation radiation. The exposure intensity also increases.

In FIG. 1(b), the exposure area 8-
1, as described in the conventional example, the lower region of the figure contains more emitted light with short wavelengths, so the exposure intensity is high in this region.

On the other hand, the exposure region 8-2 by the left-side synchrotron radiation contains more short-wavelength synchrotron radiation in the upper region of the diagram.
Exposure intensity is high.

Since the composite exposure area has a shape in which both are superimposed, exposure is made uniform and uneven exposure is eliminated.

FIG. 2 is a schematic plan view for explaining the X-ray exposure apparatus according to the present invention.

This figure is intended to make the matters described in Figure 1 clearer, and is a view from above.

In this figure, reference numeral 11 denotes an electron storage ring, in which accelerated electrons orbit in the form of an electron punch (lump) 14, and when deflected and subjected to acceleration, it emits synchrotron radiation in the tangential direction.

The spread of the luminous flux of this synchrotron radiation is about 1 mrad in the vertical direction, but about 30 mrad in the horizontal direction, and this right half of the right synchrotron radiation 1-1 is guided to the first reflection optical system 1. The first reflecting mirror 2 of the plane mirror of the first reflecting optical system 10
The light is incident on the lower surface of the , is reflected downward, and travels straight in the left and right directions. This emitted light further enters the second reflecting mirror 3, which is a toroidal mirror, and is bent upward, at the same time its spread is slightly narrowed and the entire luminous flux is bent to the left.

For the left side emitted light 1-2, the second reflection optical system 20 performs an operation exactly opposite to that for the right side emitted light 1-1.

In the above embodiment, the first and third reflecting mirrors in the front stage were plane mirrors, and the second and fourth reflecting mirrors in the rear stage were concave toroidal mirrors. It goes without saying that the present invention can obtain the same effect even if

Furthermore, the reflecting mirror rotated for exposure scanning may not be the one at the front stage, but may be at the rear stage.

〔Effect of the invention〕

As explained in detail above, in X-ray exposure using synchrotron radiation, according to the present invention, the luminous flux of the incident synchrotron radiation is divided into two left and right, and the optical path is traced approximately symmetrically with respect to the synchrotron radiation surface. After that, by overlapping them again, the exposed area can be uniformly irradiated and uneven exposure can be eliminated.

This allows microfabrication to be carried out more easily.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the X-ray exposure apparatus according to the present invention, (a) is a perspective view of the exposure apparatus, (b) is an exposure area diagram, and FIG. 2 is a schematic diagram for explaining the X-ray exposure apparatus according to the present invention. FIG. 3 is a schematic diagram for explaining a conventional X-ray exposure apparatus, in which (a) is a perspective view of the exposure apparatus, and (b) is an exposure area diagram. In these figures, ■ is synchrotron radiation, 1-1 is synchrotron radiation from the first block (right radiation) 1-2 is radiation from the second block (left radiation) 2 is radiation from the first reflecting mirror (
3 is a second reflecting mirror (toroidal mirror), 4 is a mask, 5 is a substrate (wafer), 6-1, 6-2.7-1.7-2 is reflected light, 8 is an exposure area, 8 -1 is the exposure area by the right side synchrotron radiation, 8-12 is the exposure area by the left side synchrotron radiation, 9 is the intersection, 10 is the first reflection optical system, 11 is the electron storage ring, 12 is the third reflection mirror, 13 is the fourth reflection mirror Reflector, 20 is the second reflective optical system, PA is the first exposure spot of the right side emitted light, p is the second exposure spot of the right side emitted light, QA is the first exposure spot of the left side emitted light, and QB is the first exposure spot of the left side emitted light. Second exposure spot of left synchrotron radiation (a)
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Claims (1)

[Scope of Claim] In an apparatus for projecting and exposing a mask pattern onto a substrate using synchrotron radiation, the radiation light (1-
1), the received radiation light is deflected by changing the incident angle of a reflecting mirror, and the pattern on the mask (4) is irradiated and scanned; (1) Incidence center axis direction (Z・1-Z・2)
The first reflective optical system (10) and the first reflective optical system (18) have an axis of rotational symmetry in the (W・1−W・2) direction tilted by a small angle (δ) with respect to the
It has a second reflective optical system (20) with 0° rotational symmetry, and the second reflective optical system (20) has a second block of synchronized light (1-2) which is another part of the synchronized light (1). ), the received radiation light is deflected by changing the incident angle of a reflecting mirror, and a pattern on a mask (4) is irradiated and scanned.